Modulation of osteogenesis by isolated calvaria cells: a model for tissue interactions.

Abstract

Dispersed cells from calvaria fetuses when suspended in agarose deposit a metachromic matrix. Anchorage independence is a requirement for these cells to express type II collagen. Type I collagen is preferentially expressed by cells in monolayer cultures. Cell separation by isopycnic percoll gradient showed that cells recovered from densities 1.04 g ml-1 or higher synthesized type II collagen when suspended in agarose. These cells cultured on a plastic surface expressed type I collagen. Endothelial cells isolated from rat liver or bovine aorta when implanted in diffusion chambers together with dispersed calvaria cells enhanced the formation of bone. The calcium content was 70 times higher than in chambers containing either endothelial or calvaria cells alone. The former cells developed no bone at all when implanted alone, even in the presence of demineralized bone matrix, but some isolated islands of cartilage could be seen.